Currently, smart door locks are more widely used. One of ways to operate the smart door lock is to use a digital key. In a specific method, a user accesses a smart door lock server by using a mobile device, and after performing verification on a user identity, the smart door lock server delivers a digital key to the user mobile device for storage on the user mobile device. When unlocking is needed, the user mobile device sends the digital key to a smart door lock by using a near field communications technology (e.g., NFC or Bluetooth), and the smart door lock performs verification on the digital key. If the verification succeeds, the smart door lock performs unlocking.